Product Description
Cummins 3923129 — Genuine Crankshaft Position (Engine Speed) Sensor
MPN: 3923129 | Also Known As: engine speed sensor, CKP sensor, crank sensor | Cross-Ref (ID): Mopar 4882763
Restore accurate RPM and crank position signals on your second-gen. The genuine Cummins 3923129 crankshaft position / engine speed sensor is the OE unit for 1997–1998 Ram 2500/3500 5.9L 12-valve applications that use the rectangular (square) 3-pin connector. It reads the damper at the front of the engine and feeds the ECM/PCM for idle quality, tachometer, charging strategy, and transmission logic.
Features & Benefits
- OE signal quality for stable idle, correct tach operation, and proper shifting (auto trans).
- Direct-fit sensor with factory connector and mounting pattern—no splicing.
- Durable pickup & housing for heat, vibration, and oil mist exposure near the damper.
- Fixes common symptoms: erratic/no tach, stalling, hard starts, or CKP-related DTCs (after wiring checks).
- Genuine Cummins part number for traceability and long service life.
Verified Fitment (Automotive)
| Year Range | Engine | Connector Style | Chassis |
|---|---|---|---|
| 1997–1998 | 5.9L 12V (P7100) | Rectangular / square 3-pin | Ram 2500 / Ram 3500 |
Compatibility Notes:
- Early 12-valve (’94–early ’97): commonly uses CKP 3924432 with a round connector.
- Late 1997 trucks may use this 1998-style sensor—confirm by connector shape before ordering (round = 3924432, rectangular = 3923129).
- Location: front of engine, reading the harmonic balancer/damper.
Specifications
- Type: Inductive crankshaft position / engine speed sensor
- OE Part Number: 3923129
- Connector: 3-pin rectangular (square) plug
- Mounting: Front cover/damper area; reads damper teeth
- Quantity Required: 1 per engine
Often Paired With
- Early-style CKP (round plug): Cummins 3924432 (’94–early ’97)
- CKP pigtail/repair connector (if your connector is brittle or oil-soaked)
- Harmonic balancer (damper): Cummins 3924435 (inspect while servicing)
What’s In The Box
- (1) Genuine Cummins Crankshaft Position / Engine Speed Sensor (3923129)
Installation Tips
- Key-off; disconnect negative battery cable. Safely raise front if needed for access.
- Clean the mounting area near the damper; avoid metal debris on the pickup face.
- Route the harness away from moving belts; ensure secure connector engagement.
- After install, verify stable tach reading and clear any stored CKP codes.
FAQ
WILL THIS FIT MY 1997–1998 12-VALVE RAM?
Yes—3923129 is the OE CKP/engine speed sensor for 1997–1998 trucks that use the rectangular 3-pin connector.
HOW DO I KNOW WHICH SENSOR I NEED ON A 1997 TRUCK?
Check the connector: round = 3924432 (early style), rectangular = 3923129 (late ’97–’98).
WHERE IS THE SENSOR LOCATED?
At the front of the engine, reading the harmonic balancer/damper for crank position and RPM.
WHAT SYMPTOMS POINT TO A FAILING CKP?
Intermittent/no tach, stalling, hard starts, or CKP-related DTCs. Always inspect wiring and grounds first.
IS THIS A GENUINE CUMMINS PART?
Yes—OE Cummins 3923129 (cross-ref Mopar 4882763).
